This post will give you an idea: https://blog.pixelexperience.org/2022/04/april-update-12-plus-version-is-here/
Check you're able enrol same finger or not. If yes then you've enrolled incorrectly. Reenroll your fingerprints
It is a known issue, you can flash the beta version to solve this problem
Happened to me twice! awhile back and two days ago, I suddenly couldn't open my device but I did felt every touch, looks like it worked ok but I couldn't see anything so I press some things rapidly and after a few seconds it woke up showing me everything that happened in that time in just a second and I'm guessing I accidently initiated an emergency call lol I had to apologize and hang..
Oh, then what you are talking about is animation. Can't do anything about that as it's from AOSP.No it's not possible two enroll the same finger twice. It seems also that the problem is not the scanning of the finger itself it's that the phone takes time to recognize it afterwards. For instance I can press the scanning bottom and release fastly afterwards and after I release the finger it needs a second until it unlocks. It's bummer because everything else works like charm on this ROM.